Wireless non-cellular networks, such as mesh networks, provide a new emerging technology with mesh routers and mesh clients. The wireless mesh networks contain low-cost, self-configuring nodes that automatically establish and maintain mesh connectivity. Examples of applications related to wireless mesh networks include: broadband home networking, community and neighborhood networking, enterprise networking, metropolitan area networking, transportation systems, building automation, health and medical systems and security surveillance systems.
Current mesh network systems rely on IEEE802.11 standard. Medium access control (MAC) of 802.11 standard applies carrier a sensing multiple access/distributed coordination function (CSMA/DCF) that is only a fully distributed mature MAC function. FIG. 1 shows an example of a wireless mesh network and a hidden node problem. The exemplary mesh network of FIG. 1 comprises mesh access points 100, 101, 102 and 103, hence referred to as mesh nodes. Mesh nodes 100 and 101 of FIG. 1 communicate with coverage/interference areas 200 and 201. Mesh node 102 is in the vicinity of mesh node 101. Packet collisions may appear if mesh nodes 100 and 102 try simultaneous communication 202, 204 with mesh node 101.
In a known method, time synchronization using a global positioning system (GPS) in mesh networks and distributed MAC applying DCF is provided. In DCF, the hidden node problem of FIG. 1 is solved through RTS/CTS (request to send/clear to send) protocol where mesh node 101 first sends an RTS to mesh node 101 that answers with a CTS (when transport medium is free). Then mesh node 102, that is coverage area of 101, can hear the CTS and knows that the medium is becoming busy.
However, it is widely acknowledged that DCF is not a spectrally efficient protocol. Time division multiple access (TDMA) is known to be more efficient access method than CSMA but its implementation in mesh networks is difficult due to various problems. Firstly, time synchronization between mesh nodes is missing. Secondly, a suitable distributed control mechanism should be found.